In the space and aircraft industries there is a crucial need for high-performance fastening systems. For example, a laminated frame structure consisting of layers of two or more different materials must have those layers securely fastened together at thousands of different points. A hole is formed at each location in accordance with desired criteria. Then a fastening system which passes through the hole is utilized to grip the layers of the frame structure together.
At each fastening location, there are a number of requirements which must or should be met, as follows:
(1) The parallel surfaces must be gripped throughout a predetermined area of each surface and with a predetermined amount of stress measured in a direction axial to the hole. PA1 (2) In applying the fastener, the predetermined axial stress should not be exceeded, as otherwise there might be damage to the frame material on one or both layers. PA1 (3) In applying the fastener, the fastener itself should not in any way be overstressed, as this might reduce its effectiveness. PA1 (4) The fastener when in place should be entirely secure against vibration. PA1 (5) The fastener when in place should be entirely secure against being removed. PA1 (6) The fastener when in place should be entirely secure against tampering. PA1 (7) The fastener should be constructed and/or operated in such manner that when in place, if it has been subject to tampering, it will itself provide visible evidence of such tampering.